Bug 41797 – REGRESSION (HTML5 parser?): Impossible to get past the CAPTCHA on postcode.royalmail.com

• Component: DOM
• Status: RESOLVED FIXED

[David Evans]

At the Royal Mail postcode finder site it is impossible to get past the CAPTCHA no matter how many times you try.

However, trying it with Safari without a nightly build webkit, or Firefox 3.6.4, and you will get past it in one or two goes.

Safari Version 5.0 (6533.16, r62632)

Try finding the postcode for:

Building number: 5
Street:   Rochford Avenue
Town:  Shenfield

or any other reasonable UK address.

[Alexey Proskuryakov]

How does one get to see a CAPTCHA on this site? I don't see it anywhere, all I could find mentioned was a limit of 15 searches per day.

[David Evans]

I think you have to do a few searches before you get to see the Captcha.

[Alexey Proskuryakov]

> I think you have to do a few searches before you get to see the Captcha.

I'm seeing the CAPTCHA today. The behavior is a little unstable, so it's hard to bisect to find out when this started, but I suspect HTLM5 parser.

The problem here is that we request the captcha image twice, so server side state gets out of sync with what is actually displayed.

The first request is made by normal parser, and the second one is made by preload scanner. This may or may not be a bug in loader, but preload scanner getting behind normal parsing makes no sense at all.

This probably affects more than just one site.

[Alexey Proskuryakov]

<rdar://problem/8175896>

[Adam Barth]

The second request comes from the preload scanner...  Interesting.  That could be because the preload scanner request has lower priority than the regular request.  If they get kicked off close to each other, the regular one might win.

We might need to be more agressive about canceling preload scanning.

[Alexey Proskuryakov]

> That could be because the preload scanner request has lower priority than the regular request.

I was talking about Loader::Host::addRequest(), sorry for making it too terse. Preload scanner actually sees the tag after real parser does.

[Adam Barth]

I'll look at this soon.

[Adam Barth]

Created attachment 61282 [details]
Patch

[Eric Seidel (no email)]

Comment on attachment 61282 [details]
Patch

It would be cleaner if you could get rid of the AAAAs by using an expression in php and stick them in a <div> or something which you can display none.

[Adam Barth]

Created attachment 61284 [details]
Patch

[Eric Seidel (no email)]

Comment on attachment 61284 [details]
Patch

Thanks!

[WebKit Commit Bot]

Comment on attachment 61284 [details]
Patch

Clearing flags on attachment: 61284

Committed r63154: <http://trac.webkit.org/changeset/63154>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[WebKit Review Bot]

http://trac.webkit.org/changeset/63154 might have broken GTK Linux 32-bit Release

[Eric Seidel (no email)]

Committed r63158: <http://trac.webkit.org/changeset/63158>